The idea that a diamond is an indestructible object is a common misconception. While the diamond is unparalleled in one specific measure of strength, this does not translate to total invincibility against all forms of damage. To understand if a diamond can be damaged by concrete, it is necessary to examine the scientific properties of both materials. The answer lies in distinguishing between a material’s resistance to scratching and its resistance to impact.
Understanding Hardness and the Mohs Scale
The resistance of a material to being scratched is defined as its hardness. This property is measured using the Mohs Scale of Mineral Hardness, a relative ranking system developed by Friedrich Mohs. The scale assigns numerical values from 1 to 10 based on the ability of one mineral to visibly scratch another.
The scale is purely comparative; a mineral can only be scratched by a material that is the same hardness or harder. Talc sits at the bottom with a rating of 1, while diamond occupies the maximum position at 10. The steps between numbers are not equal in absolute hardness. The jump from corundum (9) to diamond (10) represents a far greater increase in scratch resistance than the difference between any other two consecutive numbers.
The Direct Comparison: Diamond Versus Concrete
Applying the concept of Mohs hardness, concrete is composed of materials far less resistant to scratching than diamond. Concrete is a composite material consisting of cement paste and aggregates, such as sand and gravel. These aggregates, which make up the majority of the volume, often include minerals like quartz or silicates.
Hardened concrete, such as that found in floors and sidewalks, exhibits a Mohs hardness between 6 and 7. This range is comparable to minerals like feldspar or quartz, which are significantly softer than a diamond’s rating of 10. Since only a material with a Mohs rating of 10 can scratch another diamond, the softer components of concrete cannot abrade the gemstone’s surface.
Any visible mark left on a diamond after contact with concrete is not a scratch on the diamond itself. This mark is typically residue from the softer concrete material being scraped off and transferred onto the diamond’s surface. The phenomenon is similar to rubbing chalk on glass; the glass is not scratched, but a softer material is left behind. The diamond’s resistance to abrasion ensures that it remains unscratched by the material it is dragged across.
Cleavage, Impact, and Other Ways Diamonds Are Damaged
While a diamond is the hardest natural material, its resistance to scratching is only one measure of durability. A different property called toughness measures a material’s ability to resist breaking, chipping, or fracturing from impact. In this regard, diamond is rated only fair to good, a vulnerability that stems from its crystal structure.
Diamonds possess a characteristic known as perfect cleavage, which refers to the tendency of a crystalline material to split smoothly along specific planes of weakness. These cleavage planes exist because the atomic bonds are weaker in these four specific directions. A sharp, focused blow to a diamond, especially if it aligns with one of these planes, can cause the stone to chip or shatter, which is a structural failure distinct from a surface scratch.
Dropping a diamond onto a concrete surface at a particular angle can cause damage, not by scratching it, but by initiating a fracture along one of its cleavage planes. The impact of the fall provides the mechanical force necessary to exploit this structural weakness. This means the diamond is highly resistant to the abrasive action of concrete but remains vulnerable to the blunt force trauma that an accidental drop can deliver.